As shown in FIG. 1 and FIG. 2, the prior art for bar stool pedal ring raising and lowering mechanism 1 employs one-fix-point design, which comprises a main shaft 11, a pedal ring 12, a cross-shaped support frame 13 with a central tube 14, a C-type sleeve 15, a screw 17, and a screw hole 16 on the middle section of the central tube 14. The pedal ring 12 is connected to the cross-shaped support frame. Through the screw hole 16, the screw 17 serves to fasten the vertical position of the pedal ring 12. When the screw 17 rotates onto the main shaft 11, it presses the C-type sleeve 15 onto the main shaft 11. This prior art design not only need strenuous effort in the fastening process, but also has the following defects:
1. The C-type sleeve 15 is made of plastic material, which has a function to increase the strain force between the screw 17 and the main shaft 11. But when the screw 17 presses the C-type sleeve 15, it damages the surface of the C-type sleeve 15, in the long run the C-type sleeve 15 loses its function.
2. The localized pressure due to one-fix-point design also causes the deformation of the main shaft 11 to decrease the function of the bar stool pedal ring raising and lowering mechanism 1.
3. The vertical position of the pedal ring 12 is fixed only by the screw 17.
As a result, when the user put the foot on the pedal ring 12, the weight of the user tilts the pedal ring 12 and also causes the deformation of the main shaft 11.
As mentioned above, one-fix-point design causes the damage on the C-type sleeve 15 and the deformation of the main shaft 11. The pedal ring 12 and the cross-shaped support frame 13 are easy to be tilted. It endangers the user who is using it.